Welcome to Just Answer. I am here to help you resolve your tax and finance concerns. Please feel free to ask anytime you need extra help.
The concept of "getting too big a refund" is misunderstood. If you have actually overpaid your taxes by a large amount, the one being injured here is you. You have deprived yourself of the use of funds.
Too big a refund is not something the IRS is concerned about unless you have obviously committed tax fraud. Your return may be pulled for a desk review. In the process it will be compared with the prior year to see what has changed. If the taxes you paid in are similar to the prior year it will become obvious that something in the income/loss area has changed and that will be looked at. If it is questionable you may be selected for an audit. If so selected and your records are in excellent condition, you have no reason to be concerned. I would suggest that you make sure your records are in excellent order as a "just in case" security. I have had clients receive refunds well over $100,000 in refunds due to unanticipated losses without any IRS repercussions.
If you still concerned, please provide me greater specifics and I will address them for you.