No degrees of separation. Nick Lachey described his and ex-wife Jessica Simpson’s recent plane run-in on “Watch What Happens Live” Wednesday. The 98 Degrees member, 52, dubbed the March 29 reunion “strangely OK,” pointing out that “it’s been 20 years” since he was married to Simpson . Nick Lachey spoke about his and Jessica Simpson’s recent plane run-in on “Watch What Happens Live” Wednesday. Bravo The interaction was “strangely OK” and “fine,” the 98 Degrees member claimed. Bravo “We hadn’t seen each other in those 20 years, then spent six and a half hours on a flight to Hawaii together,” he noted — before clarifying they were simply “in the same vicinity.” According to Lachey, “everyone was very, very cordial” and “very respectful.” The “Perfect Match” host’s “whole family” — wife Vanessa Lachey and their three children — were onboard the flight from Los Angeles.…