Jords, I think there is no such thing as a 'bad habit' at your baby's age. She is far too young and she has far too many mental and developmental milestones to go through yet, and each time she does it will upset everything!! There is nothing wrong with taking the path of least resistance at the moment. In saying that I remember thinking the same thing when Jett was the same age, but no, nothing stayed the same and no bad habits have been formed yet!!

As for putting her down and her waking up, it may be a physical evironment thing. Eg. If you are putting her down from being warm, snug and cosy in your arms in to a bed with cold sheets that would be enough to wake anyone up. If you have cotton sheets, maybe try flanelette? It may also be a space thing, you are cuddling her close and then you put her down, to her it could be in the middle of space IYKWIM. She doesn't have that contact with you anymore so suddenly feels alone. I used to put a firm hand over Jett's belly until he resettled when I put him down, seemed to work for him.

Goodluck!