I sure as heck did! We saw them play 2 games vs. the Orioles in 1969, the year Baltimore played the Miracle Mets in the World Series. Mike Cuellar pitching the first game, Dave McNally the 2nd. We saw Boog Powell hit an inside-the-park home run in Sicks Stadium.
Sicks Stadium had to be the all time worst MLB ballpark ever. If there were a crowd in excess of about 12,000, the toilets wouldn't have enough water pressure to flush and would overflow.
The way that Seattle secured the Mariners was then WA State Attorney General Slade Gorton successfully won a lawsuit against MLB for moving the team as the stadium that later became known as the Kingdome was approved on the premise that MLB would award Seattle with a team to occupy it. When the Pilots left Seattle after just one season, the city and the state were left holding the bag, so to speak. MLB settled the lawsuit by awarding Seattle with another team, ie the Mariners.