I found a sentence I don't understand. The sentence is from a recent Scientific American article, "Sweet and Soiled Science," and I've reproduced the first paragraph here.What makes the sap run? Because he or she wants to serve in Congress. Well, that's the first answer that springs to mind this autumn day just after the November elections, and we'll get back to that subject later. But a better answer deals with a better interpretation of the question--regarding maple syrup. That subject was also on my mind, I having recently returned from a trip to the Proctor Maple Research Center in Underhill Center, Vt., while attending the annual meeting of the Society of Environmental Journalists in Burlington.
Is the phrase "I having" in the third sentence correct? Is it just not a common form? It just didn't sit well.