My girlfriend keeps touching me in public?

My girlfriend keeps touching me in public. she will grab my bulge "over my pants" while we are standing in line at the store. or at the movies to get popcorn. Or while we are walking in the mall she will grab it as we walk. She says she does it cause i turn red. What do i do. Its kinda wierd i have never had a gf that has done this before. Am i lucky. or is it wierd