Since I don't do weight lifting Scott, I really don't have an answer for you, but it is a rather interesting one & hopefully someone will come along w/some insight.
I would just advise you to take it easy for a while & if these symptoms persist, call your cardio & see what he thinks. Take care!
May/1975: AVR & MVR -- St. Luke's, Houston TX (Denton Cooley, Surgeon)
Dec/1975: MV Repair -- St. Luke's (Dr. Cooley)
Mar/2006: AVR -- St. Luke's, Houston TX (George Reul, Surgeon)
"Nothing in life is to be feared, it is only to be understood. Now is the time to understand more, so that we may fear less."
- Marie Curie