i asked that question because after graduation you would probably be in OPT. traveling in OPT would be lil tough situation to go of the US. It's good that you won't be traveling in OPT. I've not been in your situation but you need to get the visa when u come back to school. Since you are coming to US before graduation , there is a good chances that you will be granted visa again coz you still have valid F1 status. Finishing the undergraduate degree in 5,5 years is fine. Just to be prepared, you might think of some valid explanation why this happened. But i don't think this would be any issue.