HSL send could combine multiple messages in one packet?

I'm writing an iRule to use HSL::send to log HTTP request headers, and response headers.

when HTTP_REQUEST {
    HSL::send $hsl "[HTTP::request]\r\n"
}
when HTTP_RESPONSE {
    HSL::send $hsl "[HTTP::response]\r\n"
}

It turns out that inconsistently on the log receiver I could get one packet with a request + response concatenated together. I'm using TCP between BIG-IP and the log server. I wonder if this could happen for different connections as well? That is, the request and response from distinct connections combined in one packet? How to avoid this situation?