3 Long Warning Beeps

Hello all, today I heard, for the 1st time, a sequence of 3 long beeps from my MacBook Air 11' mid 2011. It was in sleep mode but felt extremely hot. Also I noticed that the battery had gone from 96% when I put it to sleep to 65% in the 15 minutes that it was asleep! When I opened it up it didn't start, pressed the power button for 5-6 seconds and thankfully it powered up and I was taken to the login screen. Have been using it now for last hour and battery use is normal.

After some frantic googling it seems that the 3 beeps are a warning for bad ram? Is it possible to swap out the ram? Would be confident enough of opening up my beloved, have previously used ifixit for iPhone 3G & 4 parts/guides so hopefully this can be done!

thnaks for taking the time to read my question :)