Upvote:2
This will not be a problem.
Since you will visit Central America you qualify for a new VWP (Visa Waiver Program) period when you re-enter the US. If you do that it's irrelevant whether it happens more or less than 90 days from your first entry.
If you enter the second time from Mexico, Canada or the Caribbean they may assume you can enter on the same VWP. This will actually not be a problem either since you will leave less then 90 days before your first entry.
Either way you will not have a problem.