The full sentence I used was "I heard you had Diwali next week, will you celebrate?".
The auto-complete functionality of a Google search for "I heard you had" provides a lot of results, like "I heard you had a ruff day.". So my assumption is that in general, the construct "I heard you had ..." should be fine. Is that the case? In addition, is my first example sentence about Diwali grammatically correct?