How does incurred vs. reimbursement work within the context of the IRS?

For example, an employee completes a course in fall 2007. Employer reimbursement of $5,000 is made in early 2008 after paperwork has been submitted.

Employee takes another course in spring 2008. Employer is willing to reimburse another $5,000 for 2008 course, but is non-taxable?

IRS regs not clear. I know $5,250 is non-taxable per calendar year. But does the first reimbursement made in 2008 for the 2007 course count as a 2007 calendar year reimbursement?

Thanks for any guidance.

Just an FYI in case anyone views this question...I spoke to the IRS (Harry Beker's office) and the IRS goes by the date the cost for the course/class was incurred. So an employee could receive tax-free reimbursement in excess of $5,250 in a calendar year if the excess was reimbursement for a prior year course. This is informal guidance.