Depends on how formal she spells it (love, luv, wuv), and how she uses it.

Usually anything other then 'love' is infromal and playful/friendly (maybe positive is better then friendly). This is usually a response thats used when your funny, intelligent, or impress her in some way.

Sometimes its used as a kinda Neg, but still playful and positive. You bust her balls and she says thats why she luvs you.

If the context is more serious, like if you comment about you likeing her personality (or something) and she responds that she 'loves you' or is 'in love with you'...thats just weird.

With the above anything thats not serious (and weird) could be played off...just keep pushing, or simply resipricate. If she used it as a Neg tell her you luv that she snorts when she laff's (or some other charater trait). If she says she loves you (because your humorous), then maybe compliment her, use of 'wuv' or 'luv' is optional.

If its just wierd id run, fast...stop typing and/or reading this and run, shes probably outside your window watching...

Hope this helps.