Tensor Fascia Latae Not a coffee drink...
It's part of your ITB (Iliotibial band) that runs along the side of your leg. If you place your hand in your pocket before sliding it all the way in, your hand will be resting right on your TFL. Connects from the top of the pelvic crest down to the greater trochanter. Different things can irritate this muscle. People that have change in their pocket etc.. can set TP's off in it.
As far as benching and it being affected
Are you tightening your legs and pressing your feet hard into the floor? Or are you a sissy with your feet planted on the bench as you lift?
It's a hip abductor and flexor. So either you are rotating your hip to the side as you heave the weight up and maybe simuletaneously flexing your legs to get the weight up. Watch your form. It's for the chest not your legs LOL
Pretty soon you'll be running around naked and shooting guns with your form