HOW long was the plane flight back? Were you able to get up and MOOOVE around much or not? You had gone on vacation, did Lots of things probably, and then had to SIT Stand, SIT for extended periods of time?
I know I feel like a geriatric [not there YET I surely hope!] when I've got to SIT for any period of time over 30 minutes! I get up and walk around the house, go to a store [just to walk] and up and down the driveway just to keep things 'rolling'...
Just hope it's nothing airline related = EVIL! - j