D.B.
All kids go through phases, preferring Mom over Dad, Dad over Mom, Grandma over Mom, and so on. Being able to roll with the punches is really a critical skill in parenting. Look at it this way - you'll be so incredibly prepared for adolescence, when kids want nothing to do with their parents!
You did the right thing, taking care of your husband in the ICU. It's great that you had in-laws to help and be there during the day. I know how hard it is to be needed in the hospital but also needed at home. You chose wisely - you went for the one in crisis (your husband) and let your baby connect with others.
Long term, children are strengthened by knowing there are others who can and will take care of them. They need to be cared for, fed and put to bed by Mom, Dad, grandparents, aunts/uncles, and babysitters. Knowing they are surrounded by love makes them more secure.
Kids also bond, at least short term, with the one who is caring for them. Some kids dont' transition well at certain ages. That doesn't mean they don't love you, and at 7 months (or 17 or 27 months) they certainly don't think you're boring!
Now, whether your MIL is milking this situation to tick you off, I don't know. I do think laughing it off is a good strategy, especially since you live there. The more confidence you display, now and in the future, the better it is for your daughter, and the more it disarms your MIL. Don't let anyone see that it bothers you, and better yet, don' let it bother you!
This will change, I promise you. And a child's closest relationship will always be with her parens, especially the parent of the same sex. You have 17.5 more years of this. Bide your time and try to feel more secure about this.