Well, no. Jealousy is, actually extremely normal and not weird at all. The vast, vast majority of people in sexual relationships do feel jealousy and it is exceptionally unusual to feel none - which is why some are wondering if your husband just doesn't actually have strong feelings for you at all.
Obviously, excessive jealousy can be problematic. But no, it's not unusual, it's a standard and very normal human trait - that's simply a fact. Obviously, we're not just apes and we can certainly control our emotions and do not have to give in to damaging impulses, but no it's definitely not strange to feel jealous in a romantic relationship.
But it is, in fact, very strange not to. You are conflating feeling jealousy with acting on it. Nearly everyone does, in fact, feel it in circumstances such as the one you are describing. But of course that doesn't mean we have to do anything concerning because of it.
There are good evolutionary reasons for why most humans in monogamous relationships feel jealousy, it's a well studied field.
https://scienceinsights.org/why-does-jealousy-exist-evolution-and-psychology/
"Jealousy exists because it solved a critical survival problem: keeping relationships and resources from being taken by someone else. It evolved as an emotional alarm system that detects threats to valued bonds, whether romantic partnerships, parental attention, or social standing. Far from being a flaw in human psychology, jealousy is one of the oldest and most deeply wired emotions, appearing in infants as young as six months old and sharing biological roots with other social species"
https://scienceinsights.org/why-does-jealousy-exist-evolution-and-psychology/
"No doubt, jealousy is shaped in part by learning and culture. But did culture really create jealousy out of nothing? Could we really just as easily learn to be overjoyed about our partners cheating on us as to have our hearts torn in two? And are there really cultures where people are indifferent to their partner's "extracurricular" sexual activities? According to evolutionary psychologists, the answer to all these questions is no. Jealousy is part of our nature, found in people all over the world. Claims to the contrary, argue the evolutionary psychologists, tend to crumble on closer inspection...
So, no, it's simply not true that someone pointing out that a total and complete lack of jealousy might signal apathy or indifference is "worrying" - it's just an observation based on the majority of relationships.
Unless, of course, you consider the great majority of all hetero relationships worrying.