Possibly - However, the rates are SOOO low, the difference in the rate is nominal. Look at the actual savings - .125% or 1/8th less on a 300,000 loan amount will save you about $20/month.
You have to factor this into your decision making process.
What are the odds your plans change and you hold onto the property outside 10 years? You might need to refinance again to get out of the Adjustable term after the 10 year fixed portion is over - and now you have closing costs again.
What are the rates going to do in the next 10 years? Statistics say they simply won't be lower - so you are locking in at a great time, with some assurance of having a solid rate in the future compared to almost guaranteed increased rates.
You MIGHT be able to sell it and allow buyer to assume your mortgage as well, which can be attractive if your loan is 3.5% and the current rates are 5.0%.
Food for thought - but the real answer here is its based on your personal circumstances.
I'd be delighted to answer any further questions you might have. Simply message me from the contact information in my profile! :)