Definitely get a spotter for the trapeze there. You never know what can happen when you fly off the bed at a weird angle. :D
Seriously though, I have had a right hip flexor/sartorius/psoas problem for several years now. They all attach in a similar (roughly) area, and it's hard for me to say which one it might be. My solution was a massage therapist (I'll take "the rapist" for 100 Trebec!) and good stretching. Combine that with high leg lifts while watching TV and those muscles are strong enough and balanced enough now to handle it.
Once every couple of months it bugs me for a day or two but that is normally when I am doing something wrong on the bike...like letting my knees go too far inwards or something stupid.