MBA: Delete files, no change in storage amount

So I'm relatively new to Macs.

So I decided to check how much storage I have remaining on my Mac, it says 31.98 GB free. Well I've been meaning to clean up my music by deleting the songs I don't listen to on albums, and I had about 5gb of videos to move to my external harddrive I never got to. So I did all that, everything is deleted from trash.

I'm feeling good, about to see approx 40gb free, click the About this Mac, click More Info, click Storage.......

...31.98 GB free.

:(

What is the reason for this, do I have to reboot to get it to update the number? I googled but couldnt find any info.