Need help, Bad eating habit!

So have a question for all you moms out there-
My 11 month old has started a bad habit when she eats, in between bites (while I'm spoon feeding her, not when she's eating on her own) she will put her arm in her mouth and suck on it till she gives herself a hickey! There doesn't seem to be any obvious reason for it, She's not teething at the moment, She doesn't do this any other time, it's not the temp of the food I always have it about room temp, there doesn't seem to be any anxiety, frustration or attitude behind it, it isn't any specific foods and she only does it about 75% of the time she eats.
I'm stumped, anyone else ever deal with this kind of thing?

    That is a bit strange! Avery will suck on the back of her hand if she's having trouble keeping a bit of food in her mouth. I figured it's just her way of making sure it goes down her throat! I don't think it's anything to be worried about though. If she ever hurts herself she'll stop.

    Have you ever seen those long sleeved bibs? I'll try to find you a link. It might protect her arm from the hickies and maybe even discourage her from doing it!
    About Mattea
    Born: Olalla, Washington
    Current: Lexington, Kentucky
    Birth: September 06
    On since: Mar 16, 2014
    Hi everyone! New here. I'm Mamma to a wonderful baby girl Seleste, just moved from Dallas TX to Lexington KY. Currently a stay at home Mamma and feel very blessed to be able to do so:) Would love to connect with moms in our area as well!