Hip flexor strain..

[EdChap]

I damaged my left hip flexor (I assume) doing Tae Kwon Do a few months ago, rested it and seemingly recovered. I can do any lift; dead, ATG squat, lunges, split squats etc. but sometimes when I'm walking (usually first thing in the morning) I can feel a slight twinge in the same spot, it usually stretches out but is it anything I should be concerned with?

Thanks in advance,

Ed.