gpg-agent caches the passphrase for a limited time (a couple of hours if
remember correctly). to check if this is the problem try signing a file
(thereby providing gpg-agent with a passphrase) then start sup in the
same shell and check if its signs emails. the time gpg-agent caches the
passphrase can be changed with: (~/.gnupg/gpg-agent.conf)

	max-cache-ttl <SECONDS>

if the passphrase caching is not the problem you might have initiated
gpg-agent insufficiently. this is what I source from ~/.bashrc to
initiate the gpg-agent or connect to a running gpg-agent:

	if [ -f "${HOME}/.gpg-agent-info" ]; then
			. "${HOME}/.gpg-agent-info"
			export GPG_AGENT_INFO
	fi
	gpg-agent --daemon --write-env-file "${HOME}/.gpg-agent-info" --quiet &> /dev/null
	export GPG_TTY=$(tty)

if you read `man gpg-agent` it mentions that exporting GPG_TTY is
important, so if you do not do this already, it might be a good place to
start.

-- 
johs (Johannes Larsen), (+47) 41435451