<p>You may be worrying more than you need.</p>

<p>I think it's within the rules of the site to ping absolutely anyone -- but not everyone would see the ping.</p>

<p>However what's within the rules is not always the same as what people might see as reasonable. I think it would generally be reasonable to:</p>

<p>a) ping a user that you have a specific reason to contact (like an issue with a question or answer you want to raise with them beyond what would be suitable for comments -- such as extended discussion). Given your judgement of what the question was about, your ping should arguably fall under this category.</p>

<p>b) ping a user you have interacted with regularly, for any reasonable purpose consistent with your personal relationship and the (fairly lax) chat rules (this is really a personal judgement about individual interactions so it's hard to say much ... and this is what I think you're asking about. We can't really establish a policy on individual judgement about the social suitability of a ping)</p>

<p>c) ping any user who is a regular in chat, for any purpose reasonably related to what the site is for, unless they have indicated otherwise. (If you're a chat regular I think it's reasonable to expect to be pinged there)</p>
