Need to Reapply Thermal Paste?

The past couple of days, my CPU has been running very hot (around 55c) while not running a game (just every day PC usage) and I was wondering if there was a need to reapply thermal paste every few months. The whole build was done this past summer, around August. Before this last week, my temps usually hung around 38c-45c depending on what I was running, and would occasionally spike to near 50c when Id play CoD or BF3. I did some searching, and my old averages were the norm for my CPU (AMD x4 965 Black Edition) but now Im having these higher temps, and was wondering if I have to replace my CPU cooling (its currently just the stock fan and heatsink) or if I just need to reapply thermal paste (I use Arctic Coolings MX-4 thermal paste) every 6 months or so.

Ive attached my HW Monitor readings, and my CoreTemp dump as of my writing this post, as well as a screen shot of CPUID temp readings.

Id really appreciate any help anyone can provide, as this is becoming extremely irritating. I have 5 case fans, front and top fans take air in, 2 side fans and rear exhaust fan blow air out, and CPU fan blowing towards heatsink

My case is a Rosewill Challenger ( http://www.newegg.com/Product/Product.aspx?Item=N82E16811147153 ) and I have all fan slots with the largest size fan that will fit in each, so my ventilation is pretty decent.

Any help would be greatly appreciated!

 

Strange . . . something has to have happened to cause such a radical change in temps. Has the computer been bumped or jarred recently? If so the heat sink on the processor could have shifted, and is not making contact with the processor properly. It would be wise to check the heat sink and make sure it is seated properly. I've never had to re-apply thermal compound on a regular basis on any of my computers . . . I just do it when it seems the CPU isn't cooling properly.

Also, has the CPU fan slowed down any? Perhaps the fan itself is developing issues and losing RPM's. Does the motherboard support a variable fan setting? Maybe something in the bios has changed? I'd check the bios settings and see if there is something there that is affecting the fan operation.

Just a question - why do you have your top fans taking air in? It would be more efficient to have those fans expelling air from the case, since hot air rises . . . althoug to be honest with the number of fans you have in your case it wouldn't make much difference.