Should i be worried?

I built my pc in December,2013. My specs are 8 gb ram, Seasonic 520w psu, i5 4670 and r9 280x.

I cleaned it for the first time last week. I didn't remove the heatsink,though as i didn't have thermal paste. Cooler is stock.

So, i used MSI Afterburner to check my temp while playing Unity. Cpu temp in all the cores went to 75 c max whereas the gpu temp went to 81 c max. Should i be worried? If yes, what should i do?

Keep in mind, i live in India and its summers now. So, normal room temp is about 32-35 c.

No, you should not be worried. Your CPU and GPU will throttle back as necessary based on temps. AMD GPUs run hot and 75c for your CPU is not extreme. It can take more heat.

LOL it's fine, I live in Israel summer is just starting over here and I already see 55C GPU without even playing anything, but CPU is fine got Noctua C14 there so it's 30C.

Your CPU temps are a little high. I have a feeling you'd instantly fail a stress test.

I have ordered Arctic Silver 5. I would remove heatsink and clean it and apply the thermal paste. Lets see if that helps.

Which brand's R9 280X you're using?

EDIT: nevermind you've got a great GPU, same as mine, you've got excellent case so airflow is not an issue to you, I would say apply new thermal paste and make sure your case is dust free.

T-junction for Intel was around 105C for desktop versions if I recall correctly, so you're not that close to having issues. GPU is kinda hot, but then again - it's AMD, they don't know how to keep themselves cool. Put some new shiny Arctic Silver 5 and you should have the temps drop a little bit. Generally, gaming computers are under a lot of burden so changing the paste every year is kinda necessary, especially with the absense of proper cooling and you're overclocking your hardware.

+1 - turned my 965BE into a cool running chip

I don't change thermal paste unless changing heatsink. Never had any issues and I don't see how it is necessary.

You should be worried if it's getting hotter than before, but you didn't mention what your temps were like.

Your CPU is getting a bit hot IMO.

BTW don't get Artic Silver 5, is old now, much better pastes available like Gelid GC Extreme or IC Diamond 7