Let $G$ act continuously on $X$, with both $G$ and $X$ locally compact Hausdorff. One usually defines a proper action to be one for which $(g,x) \mapsto (gx,x) : G \times X \to X \times X$ is a proper map. This definition is a bit uninformative, but one can show pretty easily it is equivalent to saying that, for every compact set $K \subseteq X$, the set $\{g \in G : gK \cap K \neq \varnothing \}$ is compact in $G$.
The second characterization above is rather intuitive. It says that, for any compact set in $X$, you only have to wait a compactly long time before it is translated away from itself. Looking at things this way, we are led to consider another condition on the action which is, a priori, weaker. Namely, we can consider an action with the property that a given point only hangs around in a given compact set for a compactly long time. That is, we can consider an action such that, for each $x \in X$, the orbit mapping $g \mapsto gx : G \to X$ is a proper mapping. It is conceivable that this is actually equivalent to properness of the action, but I don't see how to prove it off the top of my head, so I pose it here as a question.
Question: Let $X$ and $G$ be locally compact Hausdorff. Suppose that, for every $x \in X$, the orbit map $g \mapsto gx : G \to X$ is proper. Does it follow that the action is proper?
I fiddled with this a bit, but didn't decide the answer. If true, I feel it should rely on some principle like the "Tube Lemma". For a little while I thought I had succeeded by applying the following claim
Claim: (False) Let $X$ be a locally compact Hausdorff space and $K$ a compact Hausdorff space. Suppose that $A \subseteq K \times X$ is a closed set with the property that, for each $k \in K$, the slice $A_k = A \cap (\{k\} \times X)$ is compact. Then $A$ is compact.
which looked plausible (roughly, a "compact union" of compact sets ought to be compact), but actually that claim is false, e.g. $A = \{ (x,1/x): 0 <x < 1\} \cup \{(0,0)\} \subseteq [0,1] \times \mathbb{R}$. I still hold out some hope that the answer to the quesion is yes, though. I feel like there is some equicontinuity or something which I am failing to exploit...? Anyway, that's quite enough half-baked speculation from me!

