Just updated, iTunes/iPhone oddity

Greetings. I just updated my mid 2010 Macbook Pro to Yosemite, seems like it went fine, still learning about it. However, one odd thing I did notice is that when I plug in my iPhone to iTunes is shows my phone has almost 7gb of free space whereas before the update it had 5gb free space showing on iTunes and the phone itself says 5gb free space. Any ideas?