diff --git a/CHANGELOG_PENDING.md b/CHANGELOG_PENDING.md
index 043c66c7e..eeafaf364 100644
--- a/CHANGELOG_PENDING.md
+++ b/CHANGELOG_PENDING.md
@@ -3,6 +3,7 @@
 \*\*
 
 Special thanks to external contributors on this release:
+@erikgrinaker
 
 Friendly reminder, we have a [bug bounty
 program](https://hackerone.com/tendermint).
@@ -19,4 +20,8 @@ program](https://hackerone.com/tendermint).
 
 ### IMPROVEMENTS:
 
+- [tools] [\#4023](https://github.com/tendermint/tendermint/issues/4023) Improved `tm-monitor` formatting of start time and avg tx throughput
+
 ### BUG FIXES:
+
+- [tools] [\#4023](https://github.com/tendermint/tendermint/issues/4023) Refresh `tm-monitor` health when validator count is updated
\ No newline at end of file
diff --git a/tools/tm-monitor/monitor/network.go b/tools/tm-monitor/monitor/network.go
index 45cf2ac3c..28cd52f2e 100644
--- a/tools/tm-monitor/monitor/network.go
+++ b/tools/tm-monitor/monitor/network.go
@@ -180,6 +180,7 @@ func (n *Network) UpdateNumValidatorsForHeight(num int, height int64) {
 	if n.Height <= height {
 		n.NumValidators = num
 	}
+	n.updateHealth()
 }
 
 func (n *Network) GetHealthString() string {
diff --git a/tools/tm-monitor/ton.go b/tools/tm-monitor/ton.go
index cad17b39c..98d8d050c 100644
--- a/tools/tm-monitor/ton.go
+++ b/tools/tm-monitor/ton.go
@@ -61,11 +61,11 @@ func (o *Ton) Stop() {
 
 func (o *Ton) printHeader() {
 	n := o.monitor.Network
-	fmt.Fprintf(o.Output, "%v up %.2f%%\n", n.StartTime(), n.Uptime())
+	fmt.Fprintf(o.Output, "%v up %.2f%%\n", n.StartTime().Format(time.RFC1123Z), n.Uptime())
 	fmt.Println()
 	fmt.Fprintf(o.Output, "Height: %d\n", n.Height)
 	fmt.Fprintf(o.Output, "Avg block time: %.3f ms\n", n.AvgBlockTime)
-	fmt.Fprintf(o.Output, "Avg tx throughput: %.0f per sec\n", n.AvgTxThroughput)
+	fmt.Fprintf(o.Output, "Avg tx throughput: %.3f per sec\n", n.AvgTxThroughput)
 	fmt.Fprintf(o.Output, "Avg block latency: %.3f ms\n", n.AvgBlockLatency)
 	fmt.Fprintf(o.Output, "Active nodes: %d/%d (health: %s) Validators: %d\n", n.NumNodesMonitoredOnline, n.NumNodesMonitored, n.GetHealthString(), n.NumValidators)
 }