My Macbook air has a temperature of 60C idle, is this normal?

Hello everyone.

When I am working with my mid 2011 MBA with the i7 processor, it quickly heats up when the load is medium/high, with a lot of fan noise. It can easily reach 90C; or 98-99 under high load. Even when idle (two or three tabs in safari, some programs open, but no processing taking place, low CPU load, around 5-10%), the temperature rarely comes under 60C. Is this behavior normal? Is it possible that I need to replace the thermal paste? (It has never been replaced since 2011). Ambient temperature is 25C.